Record of early earthquakes in the Northeastern United States provide limited information on effects in Pennsylvania until 1737, 55 years after the first permanent settlement was established. A very severe earthquake that centered in the St. Lawrence River region in 1663 may have been felt in Pennsylvania, but historical accounts are not definite. Likewise, a damaging shock at Newbury, Massachusetts, in 1727 probably affected towns in Pennsylvania. A strong earthquake on December 18, 1737, toppled chimneys at New York City and was reported felt at Boston, Massachusetts, Philadelphia, Pennsylvania, and New Castle, Delaware. Other shocks with origins outside the State were felt in 1758, 1783, and 1791. In 1800, two earthquakes (March 17 and November 29) were reported as "severe" at Philadelphia. On November 11 and 14, 1840, earthquakes at Philadelphia were accompanied by a great and unusual swell on the Delaware River.
Dishes were thrown from tables (intensity V) at Allentown by a strong shock on May 31, 1884. Thirty towns from Hartford, Connecticut, to West Chester, Pennsylvania, reported fallen bricks and cracked plaster from an earthquake apparently centered near New York City on August 10, 1884. A tremor, described as lasting 10 seconds, was felt on March 8, 1889, at Harrisburg, Philadelphia, Reading, York, and other towns in that area. The intensity was estimated at V. An extremely local earthquake on May 31, 1908, at Allentown shook down a few chimneys (VI). The disturbance was not felt over more than 150 square kilometers.
On October 29, 1934, a shock of intensity V was felt at Erie. Buildings swayed, people left theaters, and dishes were thrown from cupboards. The earthquake was felt with lesser intensity at Edinboro, Girard, Mill Village, North East, and Waterford. Another shock with very localized effects occurred in southern Blair County on July 15, 1938. Broken dishes and fallen plaster (VI) were reported at Clover Creek and Henrietta. Wells were affected in Clover Creek Valley.
The area around Sinking Spring, west of Reading, experienced minor damage from an earthquake on January 7, 1954. Plaster fell from walls (VI), dishes and bottles tumbled from shelves, and furniture was upset. Other slight damage to several brick and frame buildings was reported. The tremor was felt in western Berks County and eastern Lancaster County. During the rest of the month, many smaller shocks were felt in the vicinity of Sinking Spring.
A local disturbance probably caused by subsidence of an underground coal mine caused damage estimated at $1 million in a five-block residential area of Wilkes-Barre on February 21, 1954. Occupants fled into the street. Hundreds of homes were damaged, ceilings and cellar walls split and backyard fences fell over. Sidewalks were pushed sharply upward by a heaving motion and then collapsed. Gas and water mains snapped; methane gas rising from cracks in the earth presented a temporary emergency. Two days later (February 23), a second disturbance was reported from the same section of Wilkes-Barre. More cracks appeared in ceilings and walls of apartment buildings. Curbs pulled away from sidewalks, and street pavements buckled. Additional water and gas mains were broken.
On September 14, 1961, a moderate earthquake that was centered in the Lehigh Valley shook buildings over a broad area and alarmed many residents. There was only one report of damage - loose bricks fell from a chimney at Allentown (V). However, police and newspaper switchboards throughout the area were swamped with calls from citizens. Other places with intensity V effects included Bethlehem, Catasauqua, Coplay, Egypt, Fountain Hill, Freemansburg, Hellertown, and Weaverville.
A similar disturbance occurred on December 27, 1961, in the northeast portion and suburbs of Philadelphia. Buildings shook, dishes rattled, and other objects were disturbed. Police and newspaper offices received many calls from alarmed citizens inquiring about the loud rumbling sounds (V). Several New Jersey communities across the Delaware River experienced similar effects.
A strong local shock, measured at magnitude 4.5, cracked a wall and caused some plaster to fall (VI) at Cornwall on May 12, 1964. Slight landslides were reported in the area. In one building, a radio was knocked from a table and a wall mirror moved horizontally. Workers in an iron mine about 360 meters underground were alarmed by a "quite sever jarring motion."
A small earthquake whose epicenter was in New Jersey caused intensity V effects at Darby, and Philadelphia. The December 10, 1968, shock was measured at magnitude 2.5. Although relatively minor, it broke windows at a number of places in New Jersey. Toll booths on the Benjamin Franklin and Walt Whitman Bridges in Philadelphia trembled during the earthquake.
On December 7, 1972, slight damage (V) was reported at New Holland. In addition, Akron, Penryn, and Talmage experienced intensity V effects. The total area covered approximately 1,200 square kilometers of Berks and Lancaster Counties.
Abridged from Earthquake Information Bulletin, Volume 8, Number 4, May - June 1973, by Carl A. von Hake.
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